Primary Aims of this study will determine: 1. Effects of vitamin E supplement use (VitE) on cognitive function (CF) and 3-year change in cognitive function in women age 60 and over. Hypotheses: a) Vit E supplement users will have higher scores at baseline and less decline over 3 years on visual memory tests, compared to non-users. 2. Effects of estrogen replacement therapy (ERT) on CF measures over 3 years in women age 60 and over. Hypotheses: ERT users will have higher scores at baseline and three years on verbal memory tests than non-users. Secondary Aims will determine: 1. Effects of plasma alpha-tocopherol (a-tc) levels on CF over 3 years. Hypothesis: a-tc levels will be directly related to visual memory scores at 0 and 3 years. 2. Effects of Apolipoprotein E (ApoE) genotype on change in CF over 3 years and upon VitE and/or ERT effects: Hypotheses: a) test scores will be more likely to decline in women with one or more E4 alleles. b) associations of VitE and/or ERT with CF test scores(Aims 1 &2 above) may differ between those with and without ApoE in those with ApoE e4. Background: Cognitive loss in later life is associated with increased mortality and disability, and reduced quality of life, and may represent an early stage of dementia, possibly amenable to treatment. VitE and ERT are under study as possible means to prevent or delay progression of Alzheimer's disease (AD) and both are biologically plausible as neuroprotective agents. Less is known of their ability to preserve CF in non-demented individuals. Equivocal results of previous studies may be due to nonuniform methodology and use of non-specific or less sensitive CF tests. Methods: 575 women age 60+ will be recruited from Women's Health Initiative (WHI) Observational Study and Diet Modification Control enrollees. ERT history and vitamin supplement and medication data, already collected for WHI, will be updated. Blood samples will be collected for plasma VitE measurement and ApoE genotyping. CF will be assessed with a battery of neuropsychological tests performed on 2 occasions, 3 years apart. Tests will include measures of memory, language, visual-perceptual ability and attention, as well as assessments of functional ability and depressive symptoms. Primary analyses will specifically include tests of verbal memory, which may be more sensitive to ERT effects, and visual memory, which may be most sensitive to effects of age.